Redundant control circuit for hot melt adhesive hose assembly heater circuits and temperature sensors

ABSTRACT

A redundant control circuit comprises a pair of heater circuits for heating a hot melt adhesive hose assembly to a predetermined temperature level, and a pair of temperature sensors which are used to sense the temperature of the hot melt adhesive hose assembly and to control energization of the heater circuits in order to maintain the desired temperature level. A first one of the heater circuits would initially be electrically connected to the hot melt adhesive hose assembly electrical circuitry, and in a similar manner, a first one of the temperature sensors would likewise be electrically connected to the hot melt adhesive hose assembly electrical circuitry. Subsequently, should a failure occur within the first one of the heater circuits, then an electrical switch mechanism would be activated so as to effectively remove the first, failed heater circuit from the hot melt adhesive hose assembly electrical circuitry, and substantially simultaneously, electrically connect the second one of the heater circuits to the hot melt adhesive hose assembly electrical circuitry. Similar switching procedures would also be implemented in connection with the pair of temperature sensors should a failure occur within a first one of the temperature sensors initially incorporated within the hot melt adhesive hose assembly electrical circuitry.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

This patent application is a continuation patent application of priorU.S. patent application Ser. No. 11/123,028, which was filed on May 6,2005 now U.S. Pat. No. 7,332,692.

This patent application is related to United States patent applicationentitled HOT MELT ADHESIVE HOSE ASSEMBLY HAVING REDUNDANT COMPONENTS,which was filed on Jun. 8, 2007, and which has been assigned Ser. No.11/808,378.

FIELD OF THE INVENTION

The present invention relates generally to hot melt adhesive dispensingsystems, and more particularly to a new and improved redundant controlcircuit which effectively has redundant components inherentlyincorporated therein, such as, for example, redundant hot melt adhesiveheater circuits, and redundant hot melt adhesive temperature sensors,whereby should a failure occur within one of the hot melt adhesiveheater circuits, or within one of the hot melt adhesive temperaturesensors, switch mechanisms may be suitably actuated so as to effectivelywithdraw the failed hot melt adhesive heater circuit, or the failed hotmelt adhesive temperature sensor, from its operative or functionaldisposition within the electrical circuitry, and to substantiallysimultaneously insert the backup or redundant hot melt adhesive heatercircuit, or the backup or redundant hot melt adhesive temperaturesensor, into the control circuitry whereby the hot melt adhesive hoseassembly does not need to be replaced immediately but can besubsequently replaced in accordance with, for example, normal scheduledmaintenance procedures, the hot melt adhesive dispensing production linedoes not need to be shut down for repairs whereby extensive downtime toreplace the failed hot melt adhesive hose assembly is effectively ableto be avoided, and the hot melt adhesive dispensing production line cancontinue to operate without any production downtime.

BACKGROUND OF THE INVENTION

In connection with hot melt adhesive dispensing systems, failures cangenerally occur within two different categories, that is, mechanicalfailures due to wear, or electrical failures due to electricalmalfunctions. More particularly, in connection with the different typesof electrical failures that can be experienced, electrical failures canoccur, for example, either within the heater circuit which is used tomaintain the hot melt adhesive material, which is flowing through thehot melt adhesive hose assembly, at a predetermined temperature level,or within the temperature sensor which is operatively or thermallyassociated with the hot melt adhesive hose assembly in order toeffectively detect the temperature level of the hot melt adhesivematerial, which is flowing through the hot melt adhesive hose assembly,and to appropriately control the heater circuit so as to effectivelyensure that the desired temperature level of the hot melt adhesivematerial, which is flowing through the hot melt adhesive hose assembly,is in fact maintained. Maintenance of the proper or desired temperaturelevel of the hot melt adhesive material is of course critical in orderto ensure that the hot melt adhesive material will be properlydispensed, and provide the desired adhesive properties, once the hotmelt adhesive material is in fact deposited onto a particular substrate.In either case, that is, whether a failure is experienced in connectionwith the heater circuit, or in connection with the temperature sensor,such failures typically cause the hot-melt adhesive dispensingproduction line to be shut down for extended periods of time, in orderto implement the repair or replacement of the failed components, wherebyvaluable production time is lost.

A need therefore exists in the art for a new and improved redundantcontrol circuit, for use in conjunction with a hot melt adhesive hoseassembly, wherein redundant electrical components could effectively beincorporated such that if a failure occurs within a particularelectrical component, the failed electrical component could effectivelybe removed from its operative or functional disposition within theelectrical circuitry, and the other electrical component couldeffectively be operatively or functionally incorporated into theelectrical circuitry. In this manner, the hot melt adhesive dispensingproduction line would not need to be shut down for extended periods oftime, in order to implement the replacement of the failed hot meltadhesive hose assembly, whereby valuable production time would not belost.

SUMMARY OF THE INVENTION

The foregoing and other objectives are achieved in accordance with theteachings and principles of the present invention through the provisionof a new and improved redundant control circuit which comprises a pairof heater circuits which are adapted to be wrapped around the externalperipheral surface of a hot melt adhesive hose assembly core, and a pairof temperature sensors which are also adapted to be disposed in contactwith the external peripheral surface of the hose core. A first one ofthe heater circuits would initially be electrically connected to the hotmelt adhesive hose assembly electrical circuitry, and in a similarmanner, a first one of the temperature sensors would likewise beelectrically connected to the hot melt adhesive hose assembly electricalcircuitry. Subsequently, should a failure occur within the first one ofthe heater circuits, then an electrical switch mechanism would beactivated so as to effectively remove the first, failed heater circuitfrom the hot melt adhesive hose assembly electrical circuitry, andsubstantially simultaneously, electrically connect the second one of theheater circuits to the hot melt adhesive hose assembly electricalcircuitry. Similar switching procedures would also be implemented inconnection with the pair of temperature sensors should a failure occurwithin a first one of the temperature sensors initially incorporatedwithin the hot melt adhesive hose assembly electrical circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other features and attendant advantages of the present inventionwill be more fully appreciated from the following detailed descriptionwhen considered in connection with the accompanying drawing wherein:

The SOLE FIGURE comprises an electronic circuit diagram schematicallyillustrating the new and improved redundant control circuit, operativelyassociated with a hot melt adhesive hose assembly, and developed inaccordance with the principles and teachings of the present invention,and showing the cooperative parts thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and more particularly to the SOLE FIGUREthereof, the new and improved redundant control circuit, which has beendeveloped in accordance with the principles and teachings of the presentinvention and which shows the cooperative parts thereof, and which isadapted to be operatively associated with a hot melt adhesive hoseassembly, such as, for example, that disclosed within the aforenotedco-pending United States patent application entitled HOT MELT ADHESIVEHOSE ASSEMBLY HAVING REDUNDANT COMPONENTS, which was filed on Jun. 8,2007, and which has been assigned Ser. No. 11/808,378, is disclosed andis generally indicated by the reference character 10. As is well knownin the hot melt adhesive material dispensing art, hot melt adhesivematerial is normally supplied to a hot melt adhesive hose assembly, notshown, from a hot melt adhesive supply unit, also not shown, in a heatedstate, and a heater circuit or heater assembly is conventionallyoperatively associated with the hot melt adhesive hose assembly in orderto maintain the hot melt adhesive material at a predeterminedtemperature level, while the same is being conducted through the hotmelt adhesive hose assembly, such that the hot melt adhesive materialwill have or exhibit the proper viscosity properties when the hot meltadhesive material is dispensed from the applicator end of the hot meltadhesive hose assembly. In addition, a temperature sensor is likewiseconventionally operatively associated with the hot melt adhesive hoseassembly so as to effectively detect or sense the temperature level ofthe hot melt adhesive material being conducted through the hot meltadhesive hose assembly, and to accordingly or appropriately control theenergization of the heater circuit or heater assembly, so as to againensure the fact that the hot melt adhesive material is being heated to,and maintained at, the proper temperature level while the same is beingconducted through the hot melt adhesive hose assembly, such that the hotmelt adhesive material will have or exhibit the proper viscosityproperties when the hot melt adhesive material is dispensed from theapplicator end of the hot melt adhesive hose assembly.

As has been noted hereinbefore, electrical failures can occur within hotmelt adhesive material dispensing systems either within, for example,the heater circuit or heater assembly which is used to maintain the hotmelt adhesive material, which is flowing through the hot melt adhesivehose assembly, at a predetermined temperature level, or within thetemperature sensor which is operatively or thermally associated with thehot melt adhesive hose assembly in order to effectively detect thetemperature level of the hot melt adhesive material, which is flowingthrough the hot melt adhesive hose assembly, and to appropriatelycontrol the energization of the heater circuit or heater assembly so asto effectively ensure that the desired temperature level of the hot meltadhesive material, which is flowing through the hot melt adhesive hoseassembly, is in fact maintained. Maintenance of the proper or desiredtemperature level of the hot melt adhesive material is of coursecritical in order to ensure that the hot melt adhesive material will beproperly dispensed, and will provide the desired adhesive properties,once the hot melt adhesive material is in fact deposited onto aparticular substrate. In either case, that is, whether a failure isexperienced in connection with the heater circuit or heater assembly, orin connection with the temperature sensor, such failures typically causethe hot melt adhesive dispensing production line to be shut down forextended periods of time, in order to implement the replacement of thehot melt adhesive hose assembly, whereby valuable production time islost.

It has therefore been determined that it would be desirable toeffectively incorporate redundant heater circuits or heater assemblies,as well as redundant temperature sensors, into the hot melt adhesivehose assembly, and to provide a new and improved redundant controlcircuit for effectively controlling the activation or energization ofthe redundant heater circuits or heater assemblies, as well as theredundant temperature sensors, such that if a failure occurs within aparticular one of the heater circuits or heater assemblies, or within aparticular one of the temperature sensors, the failed heater circuit orheater assembly, or the failed temperature sensor, could readily andimmediately be effectively removed from its operative or functionaldisposition within the electrical circuitry, and the other correspondingheater circuit or heater assembly, or temperature sensor, could readilyand immediately be operatively or functionally incorporated into theelectrical circuitry. In this manner, the hot melt adhesive dispensingproduction line would not need to be shut down for extended periods oftime, in order to implement the replacement of the failed hot meltadhesive hose assembly, whereby valuable production time would not belost.

More particularly, then, it is seen that the new and improved redundantcontrol circuit 10, for achieving the aforenoted desirable results,comprises an electrical connector 12 which is adapted to receiveelectrical power from a suitable main power supply 14 which isoperatively associated with an adhesive supply unit (ASU), not shown, apair of heater circuits or heater assemblies 16,18 which areelectrically connected to the electrical connector 12 by means of afirst pair of primary power lines 20,22, and a pair of temperaturesensors 24,26 which are electrically connected to the electricalconnector 12 by means of a second pair of primary power lines 28,30. Itis noted that while each one of the temperature sensors 24,26 maycomprise, and has been designated in the SOLE FIGURE as a resistancetemperature detector (RTD), each temperature sensor 24,26 mayalternatively comprise a thermistor, or a thermocouple. It is furtherseen that the opposite ends of the first heater circuit or heaterassembly 16 are electrically connected to the first pair of primarypower lines 20,22 by means of a first pair of switch mechanisms 32,34and a first pair of auxiliary connection lines 36,38, while the oppositeends of the second heater circuit or heater assembly 18 are electricallyconnected to the first pair of primary power lines 20,22 by means of asecond pair of switch mechanisms 40,42 and a second pair of auxiliaryconnection lines 44,46.

Accordingly, it can readily be appreciated that when, for example, thefirst pair of switch mechanisms 32,34, operatively associated with thefirst heater circuit or first heater assembly 16, are both disposed attheir CLOSED positions, while the second pair of switch mechanisms40,42, operatively associated with the second heater circuit or secondheater assembly 18, are both disposed at their OPEN positions, the firstheater circuit or first heater assembly 16 will be electricallyconnected into the overall redundant control circuit 10 and will beelectrically connected to the electrical connector 12 so as to receiveelectrical power therefrom in order to heat the hot melt adhesive hoseassembly, not shown. Conversely, when, for example, the second pair ofswitch mechanisms 40,42, operatively associated with the second heatercircuit or second heater assembly 18, are both disposed at their CLOSEDpositions, while the first pair of switch mechanisms 32,34 operativelyassociated with the first heater circuit or first heater assembly 16,are both disposed at their OPEN positions, the second heater circuit orsecond heater assembly 18 will be electrically connected into theoverall redundant control circuit 10 and will be electrically connectedto the electrical connector 12 so as to receive electrical powertherefrom in order to heat the hot melt adhesive hose assembly, notshown.

Continuing further, it is similarly seen that the opposite ends of thefirst temperature sensor 24 are electrically connected to the secondpair of primary power lines 28,30 by means of a third pair ofsingle-throw, double-pole switch mechanisms 48,50 and a third pair ofauxiliary connection lines 52,54, while the opposite ends of the secondtemperature sensor 26 are electrically connected to the second pair ofprimary power lines 28,30 by means of the third pair of single-throw,double-pole switch mechanisms 48,50 and a fourth pair of auxiliaryconnection lines 56,58. It is more particularly seen that the firstsingle-throw, double-pole switch mechanism 48, of the third pair ofsingle-throw, double-pole switch mechanisms 48,50, actually comprises acommon terminal 60, a pair of alternatively selectable terminals 62, 64,and a switch member 66, while in a similar manner, the secondsingle-throw, double-pole switch mechanism 50, of the third pair ofsingle-throw, double-pole switch mechanisms 48,50, actually comprises acommon terminal 68, a pair of alternatively selectable terminals 70,72,and a switch member 74. Accordingly, as was the case with the first andsecond heater circuits or first and second heater assemblies 16,18,when, for example, the third pair of switch mechanisms 48,50 are bothdisposed at their UPPER CLOSED positions at which the switch members66,74 are disposed in contact with and electrically connected to theupper selectable terminals 62, 70, while simultaneously the switchmembers 66,74 are disposed in OPEN states with respect to the lowerselectable terminals 64,72, then the first temperature sensor 24 will beelectrically connected into the overall redundant control circuit 10 andwill be electrically connected to the electrical connector 12 so as toreceive electrical power therefrom in order to monitor the temperaturelevel of the hot melt adhesive hose assembly, not shown, so as to, inturn, effectively control the one of the first or second heatercircuits, or first or second heater assemblies, 16,18 that is currentlyelectrically connected into the overall circuit 10. Conversely, when,for example, the third pair of switch mechanisms 48,50 are both disposedat their LOWER CLOSED positions at which the switch members 66,74 aredisposed in contact with and electrically connected to the lowerselectable terminals 64,72, while simultaneously the switch members66,74 are disposed in OPEN states with respect to the upper selectableterminals 62,70, then the second temperature sensor 26 will beelectrically connected into the overall redundant control circuit 10 andwill be electrically connected to the electrical connector 12 so as toreceive electrical power therefrom in order to monitor the temperaturelevel of the hot melt adhesive hose assembly, not shown, so as to, inturn, effectively control the one of the first or second heatercircuits, or first or second heater assemblies, 16,18 that is currentlyelectrically connected into the overall redundant control circuit 10.

The redundant control circuit 10 is seen to further comprise amicrocontroller 76 which is supplied with electrical power from asecondary power supply unit 78, and it is seen that the secondary powersupply unit 78 is electrically connected to the primary power lines20,22 through means of secondary power lines 80,82, and still further,the secondary power supply unit 78 is electrically connected to themicrocontroller 76 through means of a tertiary power line 84. A voltagebackup unit 86 is electrically connected to the secondary power supplyunit 78 by means of an electrical connection line 88, and the voltagebackup unit 86 is also electrically connected to a microcontrollersupervisor unit 90 by means of an electrical connection line 92 whilethe microcontroller supervisor unit 90 is, in turn, electricallyconnected to the microcontroller 76 by means of an electrical connectionline 94. Still further, an EEPROM type memory unit 96 is electricallyconnected to the microcontroller 76 by means of an electrical connectionline 98, and it is noted that the functions and operations of thesevarious electrical components, that is, for example, the microcontroller76, the voltage backup unit 86, the microcontroller supervisor unit 90,and the EEPROM type memory unit 96 will be discussed and explainedshortly hereafter.

Continuing further, in accordance with additional featurescharacteristic of the new and improved redundant control circuit 10developed in accordance with the principles and teachings of the presentinvention, a first current-voltage transformer or converter 100 iselectrically connected to or across the primary power line 20, while asecond current-voltage transformer or converter 102 is electricallyconnected to or across the primary power line 22. The current voltagetransformers or converters 100,102 are adapted to respectively detectthe current levels within the primary power lines 20,22, whichalternatively feed power to the first or second heater circuits, orfirst or second heater assemblies, 16,18 through means of the switchmechanisms 32,34, and 40, 42, and to convert such current levels tocorresponding voltage levels which are then fed into the microcontroller76 by means of data communication lines 104,106. A firstanalog-to-digital converter 108 is incorporated within themicrocontroller 76, and the data communication lines 104,106 areelectrically connected to the first analog-to-digital converter 108whereby the incoming analog voltage levels can be converted, by means ofthe first analog-to-digital converter 108, into digital voltage valueswhich can then of course be processed by means of the microcontroller76.

In addition, a first voltage detector 110 is electrically connected to,or across, the primary power lines 20, 22 so as to detect the voltagelevel existing between the two primary power lines 20,22, and thedetected voltage level is fed into the first analog-to-digital converter108 of the microcontroller 76 by means of a data communication line 112such that the incoming analog voltage level can be converted, by meansof the first analog-to-digital converter 108, into a digital voltagevalue which can be processed by means of the microcontroller 76. In asimilar manner, second and third temperature sensor-voltage converters114,116 are respectively electrically connected to, or across, the thirdand fourth pairs of auxiliary connection lines 52,54, and 56,58, bymeans of connection lines 111,113 and 115,117, so as to detect ordetermine the voltage levels existing between the third and fourth pairsof auxiliary connection lines 52,54, and 56,58, and the detected voltagelevels are respectively fed into the first analog-to-digital converter108 of the microcontroller 76 by means of data communication lines 118,120 such that the incoming analog voltage levels can likewise beconverted, by means of the first analog-to-digital converter 108, intodigital voltage values which can be processed by means of themicrocontroller 76.

In connection with the operation of the new and improved redundantcontrol circuit 10 of the present invention, when the adhesive supplyunit, not shown, is activated, the main power supply 14 operativelyassociated with the adhesive supply unit applies or transmits power tothe electrical connector 12 whereby a direct current (DC) voltage willbe generated and the microcontroller 76 is booted or activated. TheEEPROM type memory unit 96 stores various parameters and operationalprofiles operatively associated with the different components comprisingthe electronic control circuit 10, such as, for example, the variouscurrent, voltage, power values, duty cycles, and the like, generated by,or operatively characteristic of, the heater circuits or heaterassemblies 16, 18, and the temperature sensors 24,26, as conveyed to themicrocontroller 76 by means of the aforenoted data communication lines104,106,112,118,120. Accordingly, the microcontroller 76 will retrievethe most current data stored within the EEPROM type memory unit 96, andwill perform various system checks comprising the current levels,voltage levels, power levels, the duty cycle, and the like. In addition,the microcontroller 76 will activate particular ones of the switchmechanisms 32,34,40,42,48,50, which are respectively connected to themicrocontroller 76 by means of signal lines 122,124,126,128,130,132,such that particular ones of the switch mechanisms 32,34,40,42,48,50will be moved to their CLOSED positions. In this manner, a particularone of the first or second heater circuits or heater assemblies 16,18,as well as a particular one of the first or second temperature sensors24,26, will effectively be incorporated into the operative systemcomprising the redundant control circuit 10. It is also noted that theredundant control circuit 10 further comprises a communication interface134 which is electrically connected to the microcontroller 76 by meansof a data communication line 136, and a status indication means 138which is electrically connected to the microcontroller 76 by means of adata communication line 140. The communication interface 134 maycomprise, for example, a computer keyboard, a display panel, and thelike, while the status indication means may comprise, for example, greenand red LEDs, indicator lights, and the like.

It is further noted that the voltage backup unit 86 serves severalfunctions, such as, for example, providing energy for a predeterminedtime period, such as, for example, several seconds, after the adhesivesupply unit (ASU) has, for example, initiated a shut-down of the firstor second heater circuits, or the first or second heater assemblies,16,18, in accordance with an end-of-cycle mode of operation wherein theresidual energy provided by means of the voltage backup unit 86 cannevertheless maintain the microcontroller supervisor 90 active so as to,for example, shut down the microcontroller in a controlled manner ormode. In a similar manner, the voltage backup unit 86 can provide energyduring those time periods within which the first or second heatercircuits, or the first or second heater assemblies, 16,18 are beingoperated in accordance with low duty cycles. Still further, it is notedthat in addition to the voltage detector 110 being electricallyconnected to the microcontroller 76 by means of data communication line112, the voltage detector 110 is also electrically connected to themicrocontroller supervisor 90 by means of a data communication line 142.Accordingly, if, for example, the voltage detector 110 detects asignificantly low voltage level, or the loss of voltage, for apredetermined period of time, such as, for example, several seconds,then the voltage back-up unit 86 can provide sufficient power to enablethe current operating system parameters to be stored within the EEPROMtype memory unit 96, and for the microcontroller supervisor 90 to againshut down the microcontroller 76 in a controlled manner or mode. It islastly noted that at all other times, the microcontroller supervisor 90serves to monitor the microcontroller 76 in order to determine andverify the fact that the microcontroller 76 is operating properly orwithin normal parameters.

It is to be noted that during normal hot melt adhesive dispensingoperations or procedures, or during normal hot melt adhesive applicationcycles, if, for example, the switch mechanisms 32,34 have beenpreviously moved to their CLOSED positions so as to electricallyincorporate or connect the first heater circuit or first heater assembly16 into the redundant control circuit 10, while the switch mechanisms40, 42 have been previously moved to their OPEN positions so as toelectrically disconnect or isolate the second heater circuit or secondheater assembly 18 from the redundant control circuit 10, and ifsubsequently, for example, a heater failure is detected as a result of,for example, a significant change in the heater current as detected bymeans of the current-voltage transformers or converters 100,102, and ascompared to, for example, the normal heater current profile data storedwithin the EEPROM type memory unit 96, then the microcontroller 76 willinitiate a switchover of the switch mechanisms, by means of suitablesignals transmitted over the signal lines 122,124,126,128, so as to moveswitch mechanisms 32,34 to their OPEN positions whereby the first heatercircuit or first heater assembly 16 will now be electricallydisconnected or isolated from the redundant control circuit 10, andsubstantially simultaneously therewith, to move the switch mechanisms40,42 to their CLOSED positions whereby the second heater circuit orsecond heater assembly 18 will now be electrically connected to orincorporated within the redundant control circuit 10.

It is also to be noted that a heater failure can manifest itself in theform of a ground fault in connection with, for example, the first heatercircuit or first heater assembly 16 if the first heater circuit or firstheater assembly 16 is the heater circuit or heater assembly electricallyconnected to or incorporated within the redundant control circuit 10. Inparticular, not only should the heater circuit or heater assemblycurrent values detected by means of the current-voltage converters ortransformers 100,102 effectively be in accordance with the normal heatercurrent profile data stored within the EEPROM type memory unit 96, butthe detected values should also be the same within both of the primarypower lines 20,22. If this is not the case, the first heater circuit orfirst heater assembly 16 may have a ground fault. Still yet further, ifthe current values, detected within both of the primary power lines20,22, change suddenly, although the duty cycle remains constant, thismay indicate a defective heater circuit or heater assembly whereby aswitchover between the first and second heater circuits or first andsecond heater assemblies 16,18 would again be warranted.

It is lastly noted, in connection with the operations and connections ofthe first and second heater circuits or first and second heaterassemblies 16,18 within the redundant control circuit 10, that it may bedesirable to simultaneously activate all of the switch mechanisms32,34,40,42 to their CLOSED positions such that both of the first andsecond heater circuits or first and second heater assemblies 16,18 areelectrically connected to or incorporated within the electronic controlcircuit 10 for a predeterminedly short period of time, subsequent towhich, one set of the switch mechanisms 32,34,40,42 would again beactivated so as to be disposed at their OPENED position so as to servetheir redundant objective. Activating all of the switch mechanisms 32,34,40,42 to their CLOSED positions such that both of the first andsecond heater circuits or first and second heater assemblies 16,18 areelectrically connected to or incorporated within the redundant controlcircuit 10 enables the system to operate in accordance with a “boost”mode whereby, for example, a rapid heating of the hot melt adhesive hoseassembly to the predetermined desired temperature value within arelatively short period of time may be achieved. Alternatively, both ofthe first and second heater circuits or first and second heaterassemblies 16,18 may be electrically connected to or incorporated withinthe redundant control circuit 10 under low supply voltage conditions,whereas, conversely, if the supply voltage is relatively high, the useof only one of the first and second heater circuits or first and secondheater assemblies 16,18 may be necessary.

In connection with the redundant temperature sensors 24,26, it is to benoted that during normal hot melt adhesive dispensing operations orprocedures, or during normal hot melt adhesive application cycles,switch members 66,74 may be respectively moved, for example, to theirillustrated CLOSED positions at which the switch members 66,74 will berespectively electrically connected to terminals 62,70 so as toelectrically incorporate or connect the first temperature sensor 24 intothe redundant control circuit 10, whereas conversely, the switch members66,74 will effectively be disposed at their OPEN positions with respectto terminals 64,72 so as to effectively electrically disconnect orisolate the second temperature sensor 26 from the redundant controlcircuit 10. During this time, both temperature sensors 24,26 arecontinuously monitored by means of the temperature sensor voltageconverters 114,116 respectively connected across auxiliary connectionlines 52,54, and 56,58, and any time a failure or an abnormality appearsto have been detected in connection with one of the temperature sensors24,26, the temperature sensors 24,26 will effectively be tested furtherso as to determine or verify which one of the temperature sensors 24,26is in fact actually defective. For example, both temperature sensorsshould exhibit or generate the same detected voltage values. If an openor short circuit is detected within a particular one of the temperaturesensors 24,26, then clearly that particular one of the temperaturesensors 24,26 is defective. Accordingly, if, for example, it isdetermined that temperature sensor 26 is in fact defective, then theswitch members 66,74 are maintained at their illustrated positions so asto maintain the temperature sensor 24 electrically connected to, orincorporated within, the redundant control circuit 10, and toconcomitantly maintain the temperature sensor 26 electricallydisconnected or isolated from the redundant control circuit 10. On theother hand, or conversely, if, for example, it is determined that thetemperature sensor 24 is in fact defective, then signals will betransmitted from the microcontroller 76 to the switch mechanisms 48,50,by means of signal lines 130,132, so as to cause the switch members66,74 to switch positions whereby switch member 66 will now beelectrically connected to terminal 64 and switch member 74 will beelectrically connected to terminal 72. In this manner, temperaturesensor 26 will be electrically connected to, or incorporated within, theredundant control circuit 10, and temperature sensor 24 will beelectrically disconnected or isolated from the redundant control circuit10.

Continuing further, as has been noted hereinbefore, if an abnormality isdetected in connection with the operations of the temperature sensors24,26, then the temperature sensors 24,26 must be tested in order todetermine which one of the temperature sensors 24,26 is in factoperating properly and accurately sensing the temperature level of thehot melt adhesive hose assembly. Various modes or techniques for testingthe temperature sensors 24,26 are of course envisioned. For example, inaccordance with a first mode or technique for testing the temperaturesensors 24,26, if the current that is detected, by means of therespective one of the current-voltage transformers or converters 100,102which are operatively associated with the particular one of the firstand second heater circuits or first and second heater assemblies 16,18which is electrically connected to or incorporated in the redundantcontrol circuit 10, is within a valid range of values, then thetemperature level of the hot melt adhesive hose assembly, as sensed bymeans of each one of the temperature sensors 24,26, that is, thetemperature level of the hot melt adhesive hose assembly, as sensed bymeans of both of the temperature sensors 24,26, must attain apredetermined value. If this is not the case, that is, if such atemperature level is not in fact sensed or determined by each one orboth of the temperature sensors 24,26, then either the particular one ofthe temperature sensors 24,26 which is not in fact sensing the propertemperature level is not properly mounted upon or operatively connectedto the hot melt adhesive hose assembly, or the particular one of thetemperature sensors 24,26 which is not in fact sensing the propertemperature level is defective.

In accordance with a second mode or technique for testing thetemperature sensors 24,26, it is similarly noted that the temperaturelevel of the hot melt adhesive hose assembly, as sensed by means of eachone of the temperature sensors 24,26, that is, the temperature level ofthe hot melt adhesive hose assembly, as sensed by means of both of thetemperature sensors 24,26, must attain predetermined values as afunction of the duty cycle. In other words, the temperature levels ofthe hot melt adhesive hose assembly, as sensed by means of both of thetemperature sensors 24,26, is directly proportional to the duty cycle.Accordingly, if the duty cycle is increased, an increased temperaturelevel should be sensed, and correspondingly, if the duty cycle isdecreased, a decreased temperature level should be sensed. If aparticular one of the temperature sensors 24,26 is not in fact sensingthe proper temperature level, in accordance with the pre-determinedvariations in the duty cycle, then that particular one of thetemperature sensors 24,26 is defective.

Continuing further, a last unique feature characteristic of the presentinvention will now be described. It is to be appreciated, for example,that sometimes, despite the fact that the two temperature sensors 24,26are in fact working properly, and that they are accurately sensing thetemperature level of the hot melt adhesive hose assembly, they do not infact sense and generate the same temperature values. This may be due,for example, to the fact that the temperature sensors are being utilizedin connection with relatively large applicator heads and may bephysically located at substantially different locations within theapplicator head.

Therefore, it is desirable, under such conditions, to effectively buildor configure a simulated temperature sensor which can effectivelygenerate output values which comprise averaged values with respect tothe temperature values actually sensed and generated by means of the twotemperature sensors 24,26. These averaged values generated by means ofthe simulated temperature sensor will then be utilized to ultimatelycontrol the first or second heater circuits, or first or second heaterassemblies, 16,18. Accordingly, in order to in fact achieve this featureor objective, it is noted that the redundant control circuit 10 maycomprise an additional pair of single-throw, double-pole switchmechanisms 144,146, which may be similar to the single-throw,double-pole switch mechanisms 48,50, and a simulated temperaturesensor-voltage converter 148 which is utilized in conjunction with theadditional pair of single throw, double-pole switch mechanisms 144,146.The simulated temperature sensor-voltage converter 148 is effectivelybuilt or configured from suitable hardware and software incorporatedwithin the microcontroller 76 after processing pertinent informationderived from the temperature sensor-voltage converters 114,116, and theresulting simulated temperature sensor-voltage converter 148 can beadapted to be interactive with various types of adhesive supply units.

More particularly, it is noted that the additional pair of single throw,double-pole switch mechanisms 144,146, together with the simulatedtemperature sensor-voltage converter 148, effectively form an optionalor alternative sub-circuit which may effectively be electricallyconnected to or incorporated within the overall redundant controlcircuit 10, or electrically disconnected from and isolated from theoverall redundant control circuit 10. As was the case with thesingle-throw, double-pole switch mechanisms 48,50, the single-throw,double-pole switch mechanism 144 comprises a common terminal 150, a pairof alternatively selectable terminals 152,154, and a switch member 156,and in a similar manner, the single-throw, double-pole switch mechanism146 comprises a common terminal 158, a pair of alternatively selectableterminals 160,162, and a switch member 164. Still further, it is seenthat auxiliary connection lines 166,168 respectively connect thesimulated temperature sensor-voltage converter 148 to the terminals154,162 of the switch mechanisms 144, 146, and that a data communicationline 170 connects the simulated temperature sensor-voltage converter 148to a second analog-to-digital converter 172 which is incorporated withinthe microcontroller 76. In addition, it is also seen that signal lines174,176 respectively interconnect the microcontroller 76 to the switchmechanisms 144,146 so as to cause the switch members 156,164 thereof toachieve switching functions as desired.

Accordingly, it can be appreciated still further that when the switchmembers 156,164 of the switch mechanisms 144,146 are disposed at theirillustrated positions, the temperature sensors 24,26 are electricallyconnected to or incorporated within the redundant control circuit 10 ashas been previously described. On the other hand, when it is desired toeffectively electrically connect or incorporate the simulatedtemperature sensor-voltage converter 148 within the redundant controlcircuit 10, suitable signals are transmitted from the microcontroller 76so as to cause the switch members 156,164 to switch over from theirillustrated positions, at which the switch members 156,164 arerespectively connected to terminals 152,160, to their alternativepositions at which the switch members 156,164 will be respectivelyconnected to terminals 154,162. Therefore, the first and secondtemperature sensors 24,26 are effectively disconnected or isolated fromthe redundant control circuit 10 such that their generated or sensedtemperature output signals are not utilized to control the heatercircuits or heater assemblies 16,18, however, their generated or sensedtemperature output signals, as transmitted to the microcontroller 76through means of the temperature sensor-voltage converters 114,116, arenevertheless constantly utilized in conjunction with the simulatedtemperature sensor-voltage converter 148 and the temperature levelsdeveloped by means of the simulated temperature sensor-voltage converter148 in order to more accurately control the heater circuits or heaterassemblies 16, 18. It is lastly to be noted that even when the simulatedtemperature sensor-voltage converter 148 is being employed, theredundant control circuit 10 still exhibits redundancy in that both ofthe temperature sensors 24,26 are being used to generate theirtemperature level or value outputs, and are being used in conjunctionwith the simulated temperature sensor-voltage converter 148. Inaddition, if one of the temperature sensors 24,26 proves to bedefective, or fails, the microcontroller 76 will effectively ignore thegenerated temperature level or value outputs derived from such defectiveor failed temperature sensor and will utilize the temperature level orvalue outputs derived from the other temperature sensor. Since theactive temperature sensor might be generating temperature level or valueoutputs which are higher or lower than the averaged temperature level orvalue outputs generated by both temperature sensors 24,26, themicrocontroller 76 may cause the simulated temperature sensor-voltageconverter 148 to compensate accordingly based upon the temperaturelevels or value outputs previously derived from the temperature sensors24,26 and stored, for example, as profiles within the EEPROM type memoryunit 96.

Thus, it may be seen that in accordance with the principles andteachings of the present invention, there has been disclosed anddescribed a redundant control circuit that comprises a pair of heatercircuits or heater assemblies wherein each one of the pair of heatercircuits or heater assemblies is adapted to heat a hot melt adhesivehose assembly to a predetermined temperature level, and a pair oftemperature sensors wherein each one of the temperature sensors is usedto sense the temperature of the hot melt adhesive hose assembly and tocontrol energization of the heater circuits or heater assemblies inorder to maintain the desired temperature level. A first one of theheater circuits or heater assemblies would initially be electricallyconnected to the hot melt adhesive hose assembly electrical circuitry,and in a similar manner, a first one of the temperature sensors wouldlikewise be electrically connected to the hot melt adhesive hoseassembly electrical circuitry. Subsequently, should a failure occurwithin the first one of the heater circuits or heater assemblies, thenan electrical switch mechanism would be activated so as to effectivelyremove the first, failed heater circuit or heater assembly from the hotmelt adhesive hose assembly electrical circuitry, and substantiallysimultaneously, electrically connect the second one of the heatercircuits or heater assemblies to the hot melt adhesive hose assemblyelectrical circuitry. Similar switching procedures would also beimplemented in connection with the pair of temperature sensors should afailure occur within a first one of the temperature sensors initiallyincorporated within the hot melt adhesive hose assembly electricalcircuitry.

Obviously, many variations and modifications of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims, the presentinvention may be practiced otherwise than as specifically describedherein.

1. A method of controlling electrical components of a hot melt adhesivehose assembly by means of a redundant control circuit, comprising thesteps of: providing a power source; mounting an electrical connectorupon one end portion of the hot melt adhesive hose assembly forelectrically connecting the hot melt adhesive hose assembly to saidpower source; operatively mounting a pair of heater assemblies upon thehot melt adhesive hose assembly so as to heat the hot melt adhesivematerial, fluidically conducted internally within the hot melt adhesivehose assembly, to a predetermined temperature level; operativelymounting first switching means upon the hot melt adhesive hose assemblyfor selectively electrically connecting each one of said pair of heaterassemblies to said power source by means of first power lines which areelectrically connected to said power source through means of saidelectrical connector; operatively mounting a pair of temperature sensorsupon the hot melt adhesive hose assembly so as to sense the temperaturelevel of the hot melt adhesive material, being fluidically conductedinternally within the hot melt adhesive hose assembly, whereby said pairof heater assemblies can be energized in accordance with saidtemperature levels sensed by said pair of temperature sensors so as tomaintain the temperature level of the hot melt adhesive material, beingconducted internally within the hot melt adhesive hose assembly, at saidpredetermined temperature level; operatively mounting second switchingmeans upon the hot melt adhesive hose assembly for selectivelyelectrically connecting each one of said pair of temperature sensors tosaid power source by means of second power lines which are electricallyconnected to said power source through said electrical connector;monitoring the functionality of each one of said pair of heaterassemblies; monitoring the functionality of each one of said pair oftemperature sensors; and controlling said first and second switchingmeans so as to initially electrically connect a first one of said heaterassemblies and a first one of said temperature sensors to said powersource, to electrically connect a second one of said heater assembliesto said power source while disconnecting said first one of said heaterassemblies from said power source if said first one of said heaterassemblies is determined to be defective by said first monitoring means,and to electrically connect a second one of said temperature sensors tosaid power source while disconnecting said first one of said temperaturesensors from said power source if said first one of said temperaturesensors is determined to be defective by said second monitoring means,whereby operation of the hot melt adhesive hose assembly does not haveto be shut down if one of said pair of heater assemblies and said pairof temperature sensors is defective.
 2. The method as set forth in claim1, further comprising the steps of: configuring a simulated temperaturesensor as a function of temperature data received from said pair oftemperature sensors; and providing third switching means forelectrically connecting said simulated temperature sensor to said powersource by means of said second power lines, while electricallydisconnecting said pair of temperature sensors from said second powerlines.
 3. The method as set forth in claim 1, further comprising thestep of: controlling said first and second switching means so as toelectrically connect both of said pair of heater assemblies to saidpower source so as to provide the hot melt adhesive assembly with aboost in order to rapidly heat the hot melt adhesive material beingconducted internally within the hot melt adhesive hose assembly.
 4. Themethod as set forth in claim 1, further comprising the step of: using apair of current-voltage converters electrically connected to said firstpower lines for monitoring each one of said pair of heater assemblies.5. The method as set forth in claim 1, further comprising the step of:using a voltage detector electrically connected across said first powerlines for monitoring each one of said pair of heater assemblies.
 6. Themethod as set forth in claim 1, further comprising the step of: using apair of temperature sensor-voltage converters electrically connectedacross said second power lines for monitoring each one of said pair oftemperature sensors.
 7. The method as set forth in claim 1, furthercomprising the step of: using a microcontroller to control said firstand second switching means.
 8. The method as set forth in claim 7,further comprising the step of: utilizing memory means, operativelyassociated with said microcontroller, for storing operational profilescharacteristic of said redundant control circuit, said pair of heaterassemblies, and said pair of temperature sensors.
 9. A method ofcontrolling electrical components of a hot melt adhesive hose assemblyby means of a redundant control circuit, comprising the steps of:providing a power source; mounting an electrical connector upon one endportion of the hot melt adhesive hose assembly for electricallyconnecting the hot melt adhesive hose assembly to said power source;operatively mounting a pair of heater assemblies upon the hot meltadhesive hose assembly so as to heat the hot melt adhesive material,fluidically conducted internally within the hot melt adhesive hoseassembly, to a predetermined temperature level; operatively mountingswitching means upon the hot melt adhesive hose assembly for selectivelyelectrically connecting each one of said pair of heater assemblies tosaid power source by means of power lines which are electricallyconnected to said power source through means of said electricalconnector; operatively mounting a temperature sensor upon the hot meltadhesive hose assembly so as to sense the temperature level of the hotmelt adhesive material, being fluidically conducted internally withinthe hot melt adhesive hose assembly, whereby said pair of heaterassemblies can be energized in accordance with said temperature levelssensed by said temperature sensor so as to maintain the temperaturelevel of the hot melt adhesive material, being conducted internallywithin the hot melt adhesive hose assembly, at said predeterminedtemperature level; using monitoring means to monitor the functionalityof each one of said pair of heater assemblies; and controlling saidfirst switching means so as to initially electrically connect a firstone of said heater assemblies to said power source, to electricallyconnect a second one of said heater assemblies to said power sourcewhile disconnecting said first one of said heater assemblies from saidpower source if said first one of said heater assemblies is determinedto be defective by said monitoring means, whereby operation of the hotmelt adhesive hose assembly does not have to be shut down if one of saidpair of heater assemblies is defective.
 10. The method as set forth inclaim 9, further comprising the step of: controlling said first andsecond switching means so as to electrically connect both of said pairof heater assemblies to said power source so as to provide the hot meltadhesive assembly with a boost in order to rapidly heat the hot meltadhesive material being conducted internally within the hot meltadhesive hose assembly.
 11. The method as set forth in claim 9, furthercomprising the step of: using a pair of current-voltage converterselectrically connected to said power lines for monitoring each one ofsaid pair of heater assemblies.
 12. The method as set forth in claim 9,further comprising the step of: using a voltage detector electricallyconnected across said power lines for monitoring each one of said pairof heater assemblies.
 13. The method as set forth in claim 9, furthercomprising the step of: using a microcontroller to control saidswitching means.
 14. The method as set forth in claim 13, furthercomprising the step of: utilizing memory means, operatively associatedwith said microcontroller, for storing operational profilescharacteristic of said redundant control circuit, said pair of heaterassemblies, and said temperature sensor.